Multi-point exit devices often provide a relatively high degree of strength due to the multiple latching points of the exit device. During operation, when a closed door is to be displaced to an open position, a push bar of the multi-point exit device is typically depressed so that the top and bottom latch bolts are retracted away from or out of a mating recess, and into or toward the door. The latch bolts are also often maintained in retracted positions as the door is displaced from the closed position so as to prevent the latch bolts from dragging across an adjacent surface as the door is moved between open and closed positions. For example, by retaining a bottom latch bolt in a retracted position, the bottom latch bolt may not be dragged across the floor as the door is displaced from and subsequently returned to the closed position.
Traditionally, multi-point exit devices utilize hold-open mechanisms to retain both the top and bottom latches in the retracted position until the door is returned to the closed position. Such hold open-mechanisms typically utilize a direct connection between the top latch and the bottom latch to control when the bottom latch is released from the retracted position. For example, the top latch is often connected to the bottom latch by one or more rods that exert pulling forces on the top and bottom latches to retract the latch bolts from the adjacent recess when the door is to be opened. When the door is displaced from the closed position, the rods may remain in the pulled position so as to assist in holding the latches in the retracted position.
Often, when the door is returned to the closed position, a release mechanism may contact the top latch in a manner that allows a spring to push the top latch back to the extended position, wherein the top latch bolt may again be extended into a locking engagement with the adjacent recess. The release of the top latch from the retracted position also releases one or more of the rods from the pull position, which may result in a spring associated with the bottom latch providing a force to push the bottom latch back to the extended position, as well as assist with displacing one or more of the rods from the pull position.
The connection between the top latch and the bottom latch of such hold-open mechanisms often requires relatively complex linkages. Further, the springs that displace the latches from the retracted positions typically need sufficient size to provide the requisite force needed to not only at least assist in displacing the top and bottom latches and the associated latch bolts to the extended position, but to also displace the relatively heavy rods that exert the pulling force on the top and bottom latches. For example, in at least some applications, the springs may need to be of sufficient size to displace rods that are six feet in length from the pull position. Further, besides increasing the complexity and associated costs of the multi-point exit lock device, such linkages, springs, and rods increase the weight of the door, which may in turn increase the difficulty of operation of the exit device and/or the ability to displace the door between the open and closed positions.
Additionally, the physical size of the components of concealed exit devices and/or the size of the space needed to accommodate operation of the concealed components may require the removal or a relatively large portion of the interior core material of the door. Yet, the removal of such core materials, particularly from doors constructed of materials such as wood, may relatively substantially weaken the strength of the door. Prior attempts to address such weakening of doors due to accommodating concealed components of exit devices, particularly for wood doors, has included securing a metal wrap or bracket to the door to at least attempt to strength the weakened areas of the door. Yet, such metal wraps or brackets add an additional component and increase associated costs of the door. Further, such metal wraps or brackets may not be aesthetically pleasing, particularly when applied to ornate wood doors.